"MustardMan" <nomail@nomail> wrote:
> Samuel Benge <stb### [at] hotmailcom> wrote:
> >
> > MustardMan,
> >
> > How efficient does the panel absorb light? At what angles? How many
> > points of reference will you use for your calculations? I can think of
> > two ways to do what you want.
> >
> > First way. You can shoot several rays (using trace()) from the camera,
> > to see if a shadow is cast onto parts of the panel or not. From there
> > you can get the normal of the panel's surface and calculate how much
> > light would be absorbed.
> >
> > The second option uses MegaPov's projection pattern. You make the
> > pattern utilize a copy of the sun, and test the resulting pigment with
> > eval_pigment. These tests would be averaged together to achieve an
> > approximation of how much solar energy is absorbed per-panel. This won't
> > take surface normals into consideration, though.
> >
> > Just some ideas. With any luck they made sense. Hope you succeed!
> >
> > ~Sam
>
> Hi Sam,
> Solar panels conversion ability is about 17% best case. What I have done for
> my simulation is to specify an orientation angle (Pt) and using Az and Al
> from SUNPOS, use the (simplified) calculation cos(Al-Pt)*cos(Az). This
> gives the efficiency as a 'percentage' of the maximum available power [ie.
> 0 to 1].
>
> The result can be negative (the sun is behind the panels for a short time in
> the summer). I am outputting the percentage to a file for later integration,
> but the "problem" I have is that the calculation I am doing does not take
> the shadowing of objects into consideration, hence I have to manually look
> at the scene, decide if the panels are in shade, and make sure I only
> integrate over the corresponding time period. If a shadow from a tree (for
> example) passes in front of the panels, I have to note this time and make
> sure these times are excluded from calculation.
>
> What I would like to do is to get POVray to output another variable to the
> file which tells me if a point (on one or more panels) is in shade. Then
> the integrating program can calculate merrily away, and I don't have to
> worry about shadowing at inconvienient times!
>
> Thanks,
> MM.


Here are a couple more ideas:

Align orthographic cameras up to all-white, ambient 0 versions of each of
the panels.  Animate over time for each panel.  Pull those images back in
by frame number to define a pigment in another animation* and then use
eval_pigment to sample.  Be carefull about gamma.  With the correct finish
settings, I wonder if this might even work to get each panel's average
intensity and then sum it all up inside SDL.


Define an array of points on the surface of each panel.   From each of these
points shoot a ray towards the sun, with the [OBJECT_IDENTIFIER] being a
union of everything that might cast a shadow on the panel.

*no real output intended for this one...  This anim would be for your file
i/o.

Charles

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